1. Field of the Invention
This invention relates to propulsion and control systems for watercraft, surface craft and the like.
2. Description of the Prior Art
The steering of watercraft by changing the direction of the propelling force generated by a bladed propeller is well known in boats equipped with outboard motors. Such motors are commonly mounted at the stern on an axis of rotation extending essentially parallel to a transmission shaft running downward from the motor with a screw propeller mounted at the lower end and driven by bevel gearing.
Special types have also been disclosed in which the transmission shaft extends vertically downward through a central opening in the hull or other vessel, and is likewise capable of being rotated on a vertical axis by means of a control linkage. Examples of such control linkages are described in U.S. Pat. No. 3,279,417 and German Published Application OS No. 1,781,136.
It is also known, for amphibious craft, that two screw propellers may be arranged at the stern and spaced at a distance from each other. To steer the craft, the propellers are generally capable of swing movement approximately 360.degree. about substantially vertical axes of rotation as shown in German Published Application OS No. 1,141,557. Finally, such propulsion systems have also been fitted near the four corners of the craft, each with a screw propeller capable of being controlled independently as shown in German Published Application OS No. 1,756,531. The individual propulsion units are steered such that the craft may progress either ahead, astern, laterally, or even spin around in place.
The previously known propulsion systems with screw propellers capable of swinging on approximately vertical axes of rotation generally impart sufficient maneuverability for applicable requirements to watercraft equipped with such propulsion systems. This applies particularly to amphibious vehicles having four propulsion systems mounted at the corners and controlled independently of each other. However, such independent drives mounted at the four corners of a watercraft are costly, and their handling calls for experience and skill. Further, it is not possible in the case of all craft to provide several propulsion systems with each being controlled independently. At the same time, such craft fall short of desirable maneuverability. My invention provides a propulsion system for watercraft and the like which, with comparatively simple and economical structures, will substantially improve the steerability while providing a completely novel method of steering and maneuvering.